Abstract: An elongated heat conductive assembly for heating water including a plurality of water passages equally spaced about the central axis of a heat conductive member in which an elongated electrical heating element is located on the central axis of the heat conductive member. Preferably the water passages are tubes located in a highly heat conductive member whereby the heat is trapped in the center of the conductive member from where it is transferred to the water. In one embodiment, caps are provided at the ends of the tubes so that the water enters a first end and flows to a second end and then back to the first end where it exits to the hot tub. In another embodiment, the water flows through one end to the other end from whence it flows to the hot tub. In another preferred embodiment the transfer of heat from the conductive member to the water flowing in the pipes is maximized by expanding the tubes against the walls of openings in the conductive member by applying hydraulic pressure inside the tubes.